Half of the Cornwall coastal path also fell away – prompting the National Trust, which owns the land, to close the route. A new alternative footpath has been set up inland instead.

In the landslide, rocks and debris damaged a large overflow pipe at the base of the cliff, which lets water out from the landlocked lake Loe Pool.

The narrow section of coastal footpath between Porthleven and Loe Bar, where the path has been eroded (Image: Pam Kitchen)

Loe Pool was once an estuary, but has been blocked in modern times by the expansive sand bar called Loe Bar. And monitoring water levels in Loe Pool is seen as critical to preventing flooding further up the Cober Valley towards Helston.

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The agency said: “We've set up a pump at Loe Bar, as part of our contingency arrangements to reduce risk of flooding in Helston caused by damage to the rock tunnel that discharges water from Loe Pool into sea.

"We're monitoring the situation and will take further measures if they are necessary.”